The emergency room (ER) psychiatrist confronts an increasingly diverse patient population that presents complex challenges to diagnosis and treatment in this acute setting. Such challenges include difficulties involving language barriers, interpretations of behaviors, prayer and fasting rituals, gender roles, attitudes about mental health, family issues, and other cultural issues. The Muslim patient presents the ER psychiatrist with a unique set of these complexities and challenges. The Muslim population in the United States is growing rapidly and comprises a very diverse array of cultures, racial backgrounds, languages, and Islamic traditions. The current literature is deficient in addressing this problem. This article summarizes the available relevant demographic and cultural data on the Muslim population in the US, including Islamic beliefs and practices within that population; outlines the importance of cultural competency within the psychiatric ER setting in avoiding adverse outcomes and improving care; presents two clinical vignettes to illustrate culturally relevant points in patient care; and discusses a set of guidelines and principals intended to promote cultural competency in meeting the needs of the Muslim patient in the psychiatric ER. [ABSTRACT FROM AUTHOR]